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Photometry (optics)

Index Photometry (optics)

Photometry is the science of the measurement of light, in terms of its perceived brightness to the human eye. [1]

42 relations: Candela, Colorimetry, Compact fluorescent lamp, Foot-candle, Foot-lambert, Goniophotometer, Human eye, Incandescent light bulb, Infrared, Lambert (unit), Laser pointer, Light, List of light sources, Lumen (unit), Luminance, Luminosity function, Luminous flux, Luminous intensity, Measurement, Mesopic vision, Nanometre, Phot, Photodetector, Photometer, Photometria, Photometry (astronomy), Photopic vision, Point source, Radiance, Radiant energy, Radiant flux, Radiant intensity, Radiometer, Radiometry, Reflectance, Scotopic vision, Spectrometer, Steradian, Stilb (unit), Ultraviolet, Watt, Wavelength.


The candela (or; symbol: cd) is the base unit of luminous intensity in the International System of Units (SI); that is, luminous power per unit solid angle emitted by a point light source in a particular direction.

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Colorimetry is "the science and technology used to quantify and describe physically the human color perception." It is similar to spectrophotometry, but is distinguished by its interest in reducing spectra to the physical correlates of color perception, most often the CIE 1931 XYZ color space tristimulus values and related quantities.

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Compact fluorescent lamp

A compact fluorescent lamp (CFL), also called compact fluorescent light, energy-saving light, and compact fluorescent tube, is a fluorescent lamp designed to replace an incandescent light bulb; some types fit into light fixtures designed for incandescent bulbs.

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A foot-candle (sometimes foot candle; abbreviated fc, lm/ft2, or sometimes ft-c) is a non-SI unit of illuminance or light intensity.

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A foot-lambert or footlambert (fL, sometimes fl or ft-L) is a unit of luminance in United States customary units and some other unit systems.

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A Goniophotometer is a device used for measurement of the light emitted from an object at different angles.

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Human eye

The human eye is an organ which reacts to light and pressure.

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Incandescent light bulb

An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated to such a high temperature that it glows with visible light (incandescence).

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Infrared radiation (IR) is electromagnetic radiation (EMR) with longer wavelengths than those of visible light, and is therefore generally invisible to the human eye (although IR at wavelengths up to 1050 nm from specially pulsed lasers can be seen by humans under certain conditions). It is sometimes called infrared light.

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Lambert (unit)

The lambert (symbol L, la or Lb) is a non-SI unit of luminance named for Johann Heinrich Lambert (1728–1777), a Swiss mathematician, physicist and astronomer.

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Laser pointer

A laser pointer or laser pen is a small handheld device with a power source (usually a battery) and a laser diode emitting a very narrow coherent low-powered laser beam of visible light, intended to be used to highlight something of interest by illuminating it with a small bright spot of colored light.

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Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum.

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List of light sources

This is a list of sources of light, including both natural and artificial processes that emit light.

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Lumen (unit)

The lumen (symbol: lm) is the SI derived unit of luminous flux, a measure of the total quantity of visible light emitted by a source.

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Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction.

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Luminosity function

A luminosity function or luminous efficiency function describes the average spectral sensitivity of human visual perception of brightness.

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Luminous flux

In photometry, luminous flux or luminous power is the measure of the perceived power of light.

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Luminous intensity

In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human eye.

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Measurement is the assignment of a number to a characteristic of an object or event, which can be compared with other objects or events.

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Mesopic vision

Mesopic vision is a combination of photopic vision and scotopic vision in low but not quite dark lighting situations.

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The nanometre (International spelling as used by the International Bureau of Weights and Measures; SI symbol: nm) or nanometer (American spelling) is a unit of length in the metric system, equal to one billionth (short scale) of a metre (m).

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A phot (ph) is a photometric unit of illuminance, or luminous flux through an area.

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Photosensors or photodetectors are sensors of light or other electromagnetic energy.

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A photometer, generally, is an instrument that measures light intensity or the optical properties of solutions or surfaces.

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Photometria is a book on the measurement of light by Johann Heinrich Lambert published in 1760.

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Photometry (astronomy)

Photometry is a technique of astronomy concerned with measuring the flux, or intensity of an astronomical object's electromagnetic radiation.

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Photopic vision

Photopic vision is the vision of the eye under well-lit conditions (luminance level 10 to 108 cd/m2).

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Point source

A point source is a single identifiable localised source of something.

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In radiometry, radiance is the radiant flux emitted, reflected, transmitted or received by a given surface, per unit solid angle per unit projected area.

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Radiant energy

In physics, and in particular as measured by radiometry, radiant energy is the energy of electromagnetic and gravitational radiation.

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Radiant flux

In radiometry, radiant flux or radiant power is the radiant energy emitted, reflected, transmitted or received, per unit time, and spectral flux or spectral power is the radiant flux per unit frequency or wavelength, depending on whether the spectrum is taken as a function of frequency or of wavelength.

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Radiant intensity

In radiometry, radiant intensity is the radiant flux emitted, reflected, transmitted or received, per unit solid angle, and spectral intensity is the radiant intensity per unit frequency or wavelength, depending on whether the spectrum is taken as a function of frequency or of wavelength.

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A radiometer or roentgenometer is a device for measuring the radiant flux (power) of electromagnetic radiation.

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Radiometry is a set of techniques for measuring electromagnetic radiation, including visible light.

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Reflectance of the surface of a material is its effectiveness in reflecting radiant energy.

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Scotopic vision

Scotopic vision is the vision of the eye under low-light levels.

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A spectrometer is a scientific instrument used to separate and measure spectral components of a physical phenomenon.

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No description.

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Stilb (unit)

The stilb (sb) is the CGS unit of luminance for objects that are not self-luminous.

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Ultraviolet (UV) is electromagnetic radiation with a wavelength from 10 nm to 400 nm, shorter than that of visible light but longer than X-rays.

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The watt (symbol: W) is a unit of power.

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In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.

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Redirects here:

Photometric quantities, Photometrics.


[1] https://en.wikipedia.org/wiki/Photometry_(optics)

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